Crystalline microporous material exist naturally in many varieties such as mordenite and ferrierite. Further, many kinds of artificial crystalline microporous material are known such as Zeolite-A, Zeolite-X, ZSM-Z5 (see Japanese patent Kokoku No. 46-10064), and ZSM-11 (see Japanese patent Kokoku No. 53-23280) and so on.
To manufacture the artificial crystalline microporous material described above, a method commonly referred to as "hydrothermal synthesis method" is employed which includes a mixing step to obtain an alkaline mixture liquid containing silicon dioxide (SiO.sub.2), aluminum oxide, and an organic ammonium salt, and a subsequent crystallizing step to crystallize a crystalline microporous material in the inorganic material mixture liquid using high-pressure heating.
That is, according to the hydrothermal method, it has been believed that after the preparation of the mixture liquid, the heat crystallizing steps needs to be effected with the solid mixture component thereof being in the liquid. Thus, for obtaining the high-temperature and high-pressure conditions needed for crystallization, it has been necessary to place the mixture liquid in the form of liquid within a high-pressure heating container (autoclave) and then heating it.
With the conventional hydrothermal synthesis method described above, the high-pressure heating container is expensive. Also, since the inorganic mixture liquid contains alkaline metal oxide or alkaline earth metal oxide as an oxide or as an hydroxide component thereof, the liquid is very alkaline. Therefore, to prevent corrosion due to the strong alkalinity of the liquid, it has been necessary for the high-pressure heating container to be made of e.g. stainless steel or to be provided with fluorine resin surface treatment. Thus the method involves many factors which may increase the manufacturing costs of installing manufacturing equipment. In addition, when handling such strong alkaline mixture liquids as described above, it is necessary to take appropriate and sufficient measure to ensure the safety of workers engaged in the process. Therefore, the method is also considered to be very expensive synthesis method from the standpoint of safety.
Further, the crystallizing step of the hydrothermal synthesis method requires severe reaction conditions to heat the mixture liquid at a high temperature, usually from 70.degree. C. to 200.degree. C., and even higher in some cases, for a long period extended over a few days, even more than 10 days. This also contributed to further increase in the manufacturing costs.
Additionally, in a small-scale research and development, the use of the strong alkaline mixture liquid under such high-temperature, high-pressure conditions does not allow the use of ordinary glass containers. So, there has been a demand for an improved method which allows inexpensive synthesis of crystalline microporous material under milder conditions.
In addition to the above, crystalline microporous material obtained by hydrothermal synthesis is in the form of fine particles, which needs to be molded depending on its application. Yet, these fine particles do not have caking force or property, so the molding must be effected either sintering the material under an extremely high temperature or by using a binder in combination with the material. For this reason, the sintering at very high temperature may cause melting of the surface layer of the crystal, and the use of binder may block the pores of the porous structure. In either case, there is a decrease in the ratio of the crystalline microporous structure present in the molded material, i.e. the molded material will suffer a decrease in the ratio of the porous structure per unit weight. Consequently, the resultant molded material tends to lose such properties as adsorbent activity, and catalyst activity afforded by its porous structure.